Add schema registry endpoints to rpk config for the quickstart (#1413)

Author: nvartolomei

tests/docker-compose/rpk-profile.yaml

@@ -22,3 +22,11 @@ admin_api:
     - 127.0.0.1:19644 # Admin API for Broker 1: Accessible on localhost, port 19644
     - 127.0.0.1:29644 # Admin API for Broker 2: Accessible on localhost, port 29644
     - 127.0.0.1:39644 # Admin API for Broker 3: Accessible on localhost, port 39644
+
+# Configuration for connecting to the Redpanda Schema Registry API.
+schema_registry:
+  # List of Schema Registry API endpoints.
+  addresses:
+    - 127.0.0.1:18081 # Schema Registry API for Broker 1: Accessible on localhost, port 18081
+    - 127.0.0.1:28081 # Schema Registry API for Broker 2: Accessible on localhost, port 28081
+    - 127.0.0.1:38081 # Schema Registry API for Broker 3: Accessible on localhost, port 38081